Sen. Rand Paul (R-KY) is delaying efforts to confirm former National Security Advisor Mike Waltz as U.S. ambassador to the United Nations over Waltz’s previous support for a continued U.S. troop presence in Afghanistan.

Paul told Jewish Insider on Wednesday he would not vote to support moving Waltz out of the Senate Foreign Relations Committee with a favorable recommendation, as is generally a standard part of the confirmation process. Paul’s concerns forced the committee to delay a vote, scheduled for Wednesday, to advance Waltz’s nomination.

Paul said he would vote to advance the nomination with a neutral recommendation, which would allow Waltz to move forward for consideration from the full Senate but would be an unusual black mark on Waltz’s nomination. Unless Waltz picks up Democratic support, the committee vote would be tied — preventing the nomination from moving forward — without Paul’s backing.

He explained to JI that his concerns about Waltz revolve around the former national security advisor’s previous support for an amendment in the House, led by former Rep. Liz Cheney (R-WY), that would have forced the first Trump administration to maintain a troop presence in Afghanistan unless Congress approved a full withdrawal.

“I think that has constitutional problems and really goes against a lot of things that people believe, that on initiation of war, I think the president should be limited and [Congress] initiate[s] war,” Paul said. “Once a war is executed, I don’t think Congress has any business telling President [Donald] Trump … ‘You can’t have less than 8,000 troops in Afghanistan.’”

“This was led by Liz Cheney. It was a terrible thing and very anti-Trump and so I didn’t like that,” Paul said.

He also made reference to other comments he said Waltz had made about a long-term U.S. presence in Iraq or Afghanistan, which Paul said he found unacceptable.

The Kentucky senator questioned Waltz about his support for the Cheney amendment during his confirmation hearing last week.

Senate Republicans could attempt to discharge Waltz’s nomination from the committee by a full vote of the Senate, but such a process would be time-consuming and has rarely succeeded.

Sen. Jim Risch (R-ID), the chair of the Senate Foreign Relations Committee, said during the committee’s meeting on Wednesday morning that a senator had requested the vote on Waltz be delayed until the committee’s next meeting, and placed the committee’s business meeting into recess “until further notice, as we consider Mr. Waltz further.”

The Senate has one week left in session before its monthlong August recess, though Trump has urged Senate leadership to cancel the break to continue processing nominations.